Lift mechanism for industrial trucks



March 13, 1951 LiNsKl 2,545,47

Ty MEC March 13, 1951 1. ULlNsKl LFT MECHANISM FOR INDUSTRIAL TRUCKS '4 sheets-sheet 2 Filed April 21, 1948 lNvr-:N-roR 5.4.

TTRNEY LIFT MECHANISM FOR INDUSTRIAL TRUCKS 4 Sheets-Sheet 3 Filed April 2l, 1948 INVENTOR r BY i l ATTORNEY 4 Sheets-Sheet 4 llIlIIlllIIlllll/IAIYl/f l. ULlNSKl LIFT MECHANISM FOR INDUSTRIAL TRUCKS March 13, 1951 Filed April 21, 1948 INVENTOR L www ATT'RNEY l/ Patented Mar. 13, 1951 LIFT MECHANISM FOR INDUSTRIAL TRUCKS Bronislaus I. Ulinski, Chicago, Ill., assignor to The Yale & Towne Manufacturing Company, Stamford, Conn., a corporation of Connecticut Application April 21, 1948, Serial No. 22,317

13 Claims.

This inventionrelates to an electric industrial truck of the type adapted to lift, lower, and transport heavy industrial loads. My invention relates particularly to the truck disclosed and claimed in my patent application Ser. No. 439, led January 3, 1948. In that application I show a truck adapted for lifting and vtransporting extremely heavy loads Varying from 30,000 to 45,- 000 pounds. In this application I shall describe and claim the lifting mechanism. disclosed generally in my earlier application.

In trucks of the general class to which my invention relates, it is customary to lift an elevating carriage or platform by applying thereto the pressure of a hydraulic ram, the cylinder of the ram bearing on the main frame of the truck while the ram piston -presses against the carriage. In order to impart a high lift to the elevating carriage, it is required to use a long ram piston and a long ram cylinder, the lifting movement of the carriage being equal to the length of the ram piston movement relatively to the ram cylinder. With such an arrangement, the overall height of the truck is increased rather considerably upon even limited lifting of the elevatabove parts of the truck during the lifting operation.V

As a feature of my invention through which the results I seek are achieved, I utilize hydraulic ram assemblies arranged in series, so that the elevating carriage of the truck is moved through the series or sequential operation of the ram pising carriage because the ram piston must extend above the elevating carriage and the uprights before substantial lifting movement of the carriage takes place. Moreover, an arrangement of this type is costly and difficult to maintain in operation because of the considerable length of the ram piston that must extend out of the ram cylinder in the fully elevated position of the elevating carriage.

Therefore, to obtain greater lift of the elevating carriage, chains have been used in prior art trucks. Thus, itis customary to secure one end of a sprocket chain to a carriage and the other end to a main frame of a truck of the class described, with the ram piston operating against a partA of the chain through the intermediary of sprockets. In this Way, the lifting movement of the carriage is double the effective movementof the ram piston. However, for the lifting of a heavy load such as contemplated by the use of my truck, extremely large and cumbersome chains must be used, together with expensive chain securing means and sprockets. Not only is the expense considerable, but considerable space must be set aside for the sprockets and chains and' the securing means. Even further, in order to have the proper factor of safety, a rather considerable number of chains must be used, and this further complicates the problem of providing space in the truck, and increases further the cost.

tons relatively to the cylinders of the ram assemblies.

More particularly, my invention utilizes one ram assembly adapted Ato lift the elevating mechanism or platform ofthe truck through the extension thereof, after which the operation of a second ram assembly effects the u-pward movement of the entire `first ram assembly and the elevating platform. Even more particularly, my invention utilizes what I term a base hydraulic ram assembly adapted to lift a support on which is mounted a secondary ram assembly that is adapted to limpart movementto the elevating carriage of the truck. It is thus seen that the elevating carriage is actuated by the extension of the secondary ram assembly and by the extension also of the base ram assembly.

As a detailed feature of my invention, the secondary ram assembly is adapted to be carried by the baseram assembly merely through the de posit of the secondary ram assembly on a support, gravity being utilized for effectively holding the secondary ram assembly in place.

As a further detailed feature of my invention, I utilize a novel and simple single point connection between the secondary ram assembly and each side of the elevating carriage, which in the form` of my invention here illustrated is equipped with a load lifting prong for lifting rolls of steel.

I have thus outlined rather broadly the more important, features of my invention in order thatv the detailed description thereof that follows may be better understood, and in order that my contribution to the art may be better appreciated.

There are, of course, additional features of my invention that will be described hereinafter andl which will form the subject of the claims appended hereto.; Those skilled in the art will apimportant, therefore, that the claims `to bei granted me shall be of suicient breadth to prevent the appropriation of my invention by those skilled in the art.

Referring now to the drawings, Fig. 1 is a perspective view of a truck embodying my invention. Fig. 2 is a view similar to Fig. 1, but showing the elevating carriage of the truck in its fully elevated position. Fig. 3 is an elevation of the forward or load lifting part of the truck. Fig. 4 is a section taken along lines 4--4 of Fig. 3. Fig. 5 is a schematic showing of the hydraulic mechanism of the truck.

Referring now more particularly to the drawings, the truck of my invention utilizes a main frame I3 formed by the welding of a series of structural steel members to one another as is common in this art, and as is more particularly set forth in my earlier application to which I have herein referred. Forming an integral part of the main frame I0 is a pair of uprights II, each formed as an H in section so thatv each upright II is adapted for cooperation with two sets of rollers. The elevating carriage or platform of the truck is designated generally by reference letter E, and is equipped with four plates I2 best shown in Fig. 2, there being a plate I2 at each side of each of the H-shaped uprights I I.

22 at the lower end of a ram cylinder 23, best shown in Fig. 5. Each lug 22 is formed with a groove 24 and a snap ring 25 fits in this groove and thereby secures the two ram cylinders to the base 2G while allowing considerable movement of the cylinders relatively to the base. The ram cylinders 23 are of conventional construction and each is adapted to house a hollow ram or piston 26. Each of the hollow rams or pistons 26 terminates in a shouldered portion 21 (Fig. 5) from which extends a cylindrical lug 28 threaded at 29 for a pipe 30. The two pipes 30, as best seen in Fig. 2, and as shown schematically in Fig. 5, are joined through a union 3| to a pipe 32 extending into a ram cylinder 33 forming part of what I term my secondary ram assembly, the ram cylinders 23 and ram pistons 26 comprising the Y base ram assembly.

Each plate I2 carries a pair of rollers I3 adapted for movement in the opposed channels of the uprights II. The four plates I2 are adapted to be welded together to form a unitary structure that forms the elevating carriage E. Thus, the left hand pair of plates I2, as seen in Fig. 2, are welded to a cross plate I4, in turn welded to longitudinal members I5 that are welded to a main support plate I6. Support plate I6 is adapted to carry a prong-like member P that is used for lifting the load. It will be well at this point to indicate that the manner in which the elevating carriage E is formed is not of particular importance here, it being necessary only to understand that the elevating carriage is mounted for vertical lifting movement on the uprights II from the loweredposition illustrated in Fig. 1 to the fully elevated position illustrated in Fig. 2. p

My invention contributes lifting means adapted to raise the elevating carriage E together with the extremely heavy loads for which the said carriage and the remainder of the truck are designed. My invention departs radically from the teachings of the art through the utilization of hydraulic ram assemblies operating in series or sequentially for contributing a high lift to the extremely heavy loads involved. I thus depart radically from the teachings of the prior art wherein elevating carriages receive high lift through the medium of chain mechanisms actuated by hydraulic rams, or through the utilization of secondary uprights to which lifting movement must be imparted to contribute lifting movement to the elevating carriage itself. It will be well to emphasize at this point that through the particular arrangement of lifting mechanism hereinafter to be set forth in detail, it is possible for me to contribute a high lift movement to the elevating carriage without exposing above the uprights of the truck or above the carriage any part of the lifting mechanism utilized by me.

Referring now more particularly to Fig. 4, I show there a base 20 formed as an integral part of the main frame of the truck and extending horizontally between the H uprights II. Base 20 is formed with a pair of spaced openings 2l and extending into each of these openings is a lug A support casting 34, shown best in Figs. 2 and 4, is formed'with a pair of openings 35 whereby it may be placed on the shoulders 21 of the two t Support 34 `will thus be effectively carrams 26. ried by the rams or pistons 26, vbut is preferably secured thereto by threaded washers or nuts 36,'

Support 34 is formed with a third and larger opening 3B, and within this opening there is inserted the ram cylinder 33 already referred to.

This ram cylinder is formed with an integral collar 39 best seen in Fig. 5, that fits against that part of the support 34 forming the periphery of the third opening 38. Therefore, upon vertical movement of the support 34, the ram cylinder 33V is lifted also, as will be quite apparent.

Mounted within the ram cylinder 33 is a ram pistonY 40 formed hollow substantially in the samev areas of the ram pistons 26, all for a reason which will be explained hereinafter. The upper end of the ram piston 4l]l is formed with a shoulder 4I from which extends a cylindrical lug 42 as best seen in Figs. 4 and 5. Resting on the shoulder 4I is a cross beam 43- formed with anopening 44l through which the cylindrical lug 42 extends. A threaded washer or nut 45 is secured on the threads 46 of the lug 42, but it will be appreciated that the cross beam 43 is really assembled through gravity to the ram 40 just as the support A34 is carried -by the two rams 26. It must also be appreciated that the arrangement of the cross beam and support relatively to the rams 4is such that there can be some movement therebetween to allow weaving of the parts during movement of the truck and lifting of the load.

Cross beam 43. is secured at each end thereof tol I shall now describe particularly the hydraulic.

system whereby the several rams are actuated, and for this purpose, it will be best to refer to Figs. 3 and 5. In those ngures, reference numer-' al 5B indicates a pump receiving its fluid through a pipe 5I from a reservoir 52. The pump trans'- mits fluid through a pipe 53 to a relief valve `54.l

Fluid flows from the reliefV valve 54 through pipev 56 to acontrol valve Y5l .from whence iluidjis trans-1' mitted through pipes`58 and 59 to the two base' rain cylinders 23. From the cylinders 23 uid will liow through the hollow rams 21 to the cylinder33 as has already been described.

' The three cylinders bleed into a pipe 50 rigidly connected to the two cylinders 23 while communicating with cylinder 33 through a flexible hose 6l. Pipe 50 leads through an air breather and lter 52 that in turn leads to the reservoir 52. Reservoir 52 is also connected to an oil filter 63 through a pipe 54, oil filter 63 then communicating through a pipe 65 with a pipe 63 leadingl to control valve 51. The controls `and parts thus described are entirely conventional, my invention residing in the use of the three rams and their relationship to one another and to the elevating carriage and main frame of the truck, all as I have outlined above.

Let us now consider that the elevating platform E is in its lowered position of Fig 1 with the three hydraulic rams in their solid line position of Fig. 4 and as set forth in diagrammatic Fig. 5. Let us say that it is now desired to raise the elevating platform E towards its position of Fig. 2. For this purpose, control valve 51 will be moved to its lift position simultaneouslyw actuating the pump 55 as is common 'in trucks of this class. Fluid will then ow from the reservoir 52 through pipe 5l into the pump 50 and then through pipe 53, relief valve 54, pipe 56, control valve 51, and pipes 58, 59 to the two cylinders 23. The fluid will ow from the cylinders 23 through the hollow rams 26 to the coupling 3l via pipes 30, then through pipe 32 into cylinder 33. The pressure will then be applied to the head of the hollow ram piston 40.

vSince ram piston 40 is of greater area than the sum of the areas of the two ram pistons 26 and also carries a lighter load than ram pistons 25, it will move under the force of the pressure and will raise the cross beam 43 to the dash and dotted line position of Fig. 4. This movement ofthe cross beam will, of course, elect elevating movement of the elevating carriage E to an intermediate position. Upon the full extension of the ram piston 4U withinthe cylinder 33, the pressure within the hydraulic system will be increased and then will be eifective to move the two rain pistons 26 of the base ram cylinders 23. Thereupon, ',the support 34 will move upwardly to the extended position shown in Fig. 2. The elect of this movement will be to raise the secondary ram assembly as a unit to the position of Fig. 2 whereby to complete the elevating movement of the elevating carriage E.

If it is now desired to lower the elevating carriage E, it is merely necessary to move the handle of the control valve 51 into a position to open communication of the pipes 51, 58 with'pipe 66. Fluid will now iiow from behind the three rams through the control valve 51 into pipe 66, through pipe 55, oil filter 63, into the reservoir. Of course,

fluid will first flow from behind the two base rams 26 and thereafter from behind the secondmeasure and will be well yunderstood by those skilled in the art.

I believe that the operation of my invention and its construction will now be clearly understood.

I now claim:

`1. In a truckjof the. class described, a main frame, a pair of uprights on said main frame, a load carriage slidably mounted on said uprights, a base ram cylinder, a base ram in said cylinder, means mounting said base ram cylinder and base ram for extension relatively to said main frame, a secondary ram cylinder, a secondaryramfor said secondary ram cylinder, means mounting said secondary ram cylinder and secondary ram for movement bodily by the extension of said base ram relatively to said base ram cylinder, and means securing said carriage for vertical movement by movement of said secondary ram relatively to said secondary ram cylinder and by movement of said secondary ramand cylinder bodily by said base ram.

2. In a truck of the class described, a main frame, a load carriage mounted for vertical movement relatively to said mainy frame,`a base ram cylinder, a base ram in said cylinder, means mounting said base ram cylinder and base ram for extension relatively to said main frame, a secondary ram cylinder, a secondary ram for said secondary ram cylinder, means mounting said secondary ram cylinder and secondary ram for movement bodily by the extension of said base ram relatively to said base ram cylinder, and means securing said carriage for vertical movement by movement of said secondaryram relatively to said secondary ram cylinder and by movement of said secondary ram and cylinder bodily by said base ram.

3. In a truck of the class described, a main frame, a pair of uprights on said main frame, a load carriage slidably mounted on said uprights, a base ram cylinder, a base ram in said cylinder, means mounting said base ram cylinder and base ram for extension relatively to said main frame, a secondary ram cylinder, a secondary ram for said secondary ram cylinder, means mounting said secondary ram` cylinder and secondary ram for movement bodily by the extension of said base ram relatively to said base ram cylinder, and means whereby said load carriage is moved on said uprights by movement of said secondary ram.

4. In a truck of the class described, a main fram-e, a pair of uprights on said main frame, a load carriage slidably mounted on said uprights, a base ram assembly comprising cylinder and ram means adapted for lifting extension, means mounting said base ram assembly for extension from a base forming part of said main frame, a secondary ram assembly comprising relatively movable cylinder and ram means, support means for said secondary ram assembly carried by said base ram assembly and movable vertically relatively to said base and main fram-e upon extension of the ram and cylinder means of said base ram assembly, and means securing said load carriage relatively to one of the relatively movable cylinder and ram means of said secondary ram assembly for movement thereby.

5. In a truck of theclass described, a main frame, a load carriage mounted for vertical movement relatively to said main frame, a base ram assembly comprising cylinder and ram means adapted for lifting extension, means' mounting said base ram assembly for extension from ra base forming part of said main frame, a secondary ram assembly comprising relatively movable cylinder and ram means, support means for said-secondary ram assembly carried by said base ram assembly and movable vertically relatively to said base and main frame upon extension of the rain and cylinder means of said base ram assembly, and means securing said load carriagev relatively to one of the relatively movable cylin,

der and ram means of said secondary ram as.- sembly for movement thereby.

v6. In a truck of the class described, a main frame, a pair of uprights on said main frame, a load carriage slidably mounted on said uprignts, a pair of base ram assemblies comprising each a cylinder and ram means adapted for lifting extension, means mounting said pair of base ram assemblies for extension each from a base forming part of said main frame, a secondary ram assembly comprising relatively movable cylinder and ram means, a support for said secondary ram assembly carried by and comm-on to said pair of base rain vassemblies and movable vertically relatively to said base and main frame upon extension of the ram and cylinder means of'said base ram assemblies, and means securing 'said load carriage rela-tively to one of the relatively movable cylinder and ram means of said secondary ram assembly for movement thereby.

'7. In a truck of tlie class described, a main frame, a load carriage mounted for vertical movement relatively to vsaid main frame, a pair of base ram assemblies comprising each a cylinder yand ram means adapted for lifting extension, means mounting said pair of base ram assemblies for extension each from a base forming part of said mai-n frame, a secondary ram assembly comprising relatively movable cylinder and ram means, a support for said secondary ram assembly carried by and common to said pair of base ram assemblies and movable vertically relatively to said base and main frame upon extension of the ram and cylinder mea-ns of said base ramassernblies, and means securing said load carriage relatively to one of the relatively movable cy1in der and ram means of said secondary ram assemn bly for movement thereby.

8. In a truck of the class described, a main Vframe, a pair of uprights on said main frame, a load carriage slidably mounted on said upriglits, :a pair of base ram assemblies comprising each a cylinder and ram means adapted for lifting exz'ension, means mounting said vpair of base ram assemblies for extension each from a base forming part of said main frame, a secondary ram as- ;sem-bly comprising relatively movable cylinder :and ram means, a support for said secondary ram :assembly carried by and common to said pair oi' '.base ram assemblies and movable vertically rela- :tively to said base and main frame upon extension of tneylamand cylinder means of .said base ram rassemblies, said support having an opening, the cylinder means of said secondary ram assembly extending through said opening and resting by gravity against a part of said support, and Vmeans whereby the secondary ram lifts said load car- .riage 9. In a truck of the class described, a main iframe, a pair of uprights on `said main frame, a .load carriage slidably mounted on said uprights, .a pair of base ram assemblies comprising each la cylinder and ram means adapted for lifting extension, means mounting said pair of base ram assemblies with the lower ends of the cylinders vthereof resting against a base forming part of `said main frame, a ram cylinder support carried whereby to raise said support when said rams are extended, a secondary ram cylinder carried by said support, a secondary ram in said ram cylinder, and means whereby the .secondary ram lifts said load carriage.

10. In a truck of the class described, a main frame, a pair of uprights on said main frame, a load carriage slidably mounted on said uprights, a pair of base ram assemblies comprising each a cylinder Iand ram means adapted for lifting extension, means mounting said pair of base ram assemblies with the lower ends of the cylinders thereof resting against a base forming part of said main frame, a ram cylinder support carried in common by the rams of said base cylinders whereby to raise said support when said rams are extended, said support having an opening, a secondary ram cylinder extending through said opening and resting by gravity against a part of said support, and means whereby the secondary ram lifts said load carriage.

1'1. In a truck of the class described, a ymain v frame, a pair of upriglits Yon said main frame, a

load carriage slidably mounted on said uprights, a pair of ram cylinders on said main frame, a ram slidable in each 'of said ram cylinders, a support carried by said rams, a secondary ram cylinder mounted on said support, a secondary ram in said secondary ram cylinder, la cross beam carried by said secondary ram, and pivot shafts at the ends of said beam for pivotally connecting said beam to said-carriage.

12. In a truck `of the class described, a main frame, a pair of uprights on said main frame, a load carriage slidably mounted on said uprights, a pair of ram cylinders on said main frame, a hollow ram slidable in each of said ram cylinders, a support carried by -said rams, a secondary ram cylinder mounted on -said support, means Ywhereby uid ows from said hollow rams to said secondary ram cylinder, a secondary ram in said secondary ram cylinder, a source of fluid pressure for supplying uid to said ram cylinders, and means whereby movement of said secondary ram cylinder moves lsaid carriage on said uprights.

13. In a truck of the class described, a main Trame, a load carriage mounted forvertical movement relatively to said main frame, a base ram assembly comprising cylinder and ram means adapted for lifting extension, a secondary ram assembly comprising relatively movable cylinder and ram means adapted for -lifting extension, means for lifting bodily said 'secondary ram assembly actuated by said base ram assembly and movable upon extension of the ram and cylinder means of 4said base r-am assembly, and means for lifting said `load carriage actuated by the extension of said cylinder and ram means of said secondary ram assembly.

BRoNIsLAUs i. -ULINSKL Name Date Guerin May '7, 1946 Number 

